System V Shared Memory applications

[Tim Olson]

In article <21499 at shemp.CS.UCLA.EDU> brett at CS.UCLA.EDU () writes:
| I am interested in knowing if you have ANY software
| that makes use of System V's shared memory.

I'm not sure if this is the kind of thing you are looking for, but I
used shared memory to implement the communication between a "load
daemon" and the user-invokable load average reporter on an IBM RT/PC,
which didn't have the calculated load averages in the kernel.

The load daemon updated, at 1-second intervals, a circular buffer
holding the last 15 minutes worth of run-queue sizes.  The circular
buffer and its associated pointer were kept in a shared-memory segment,
so that they could be read by user-level programs to calculate load
averages.

One benefit of this is that no set-uid program is needed to read the
kernel and report load averages.


	-- Tim Olson
	Advanced Micro Devices
	(tim at amd.com)